Antioxidants may counteract the effects of reactive oxygen species (ROS) that may accumulate acutely and chronically within cells as a consequence of environmental insults and pathologic processes. Certainly, health food stores promote this concept with sales of products such as vitamin E. However, cellular damage is multifactorial, and proving that one compound has a significant effect is difficult. Analgesics ameliorate the perception of pain from cellular damage, but they do not prevent or diminish cell damage; they only mask it. Antimicrobials may help the body's own immune defenses against infectious agents and shorten and/or diminish tissue damage. However, long-term use of antimicrobials is discouraged because it may alter the body's own useful microbial flora, and it can promote development of drug-resistant strains that pose a serious health risk for the general population. (As Mr. Spock noted, "The needs of the many outweigh the needs of the few.") Antineoplastic agents are given for malignancies and rarely have benefit for cancer prevention. Glucocorticoids provide short-term improvement in well-being, but when used for longer periods, they have deleterious effects.